In reading Psalm 139 a warning to heed is inferred in verses 19-24. It sounds like Matthew 7:1-5: “Do not judge, or you too will be judged.  For in the same way you judge others, you will be judged, and with the measure you use, it will be measured to you.  Why do you look at the speck of sawdust in your brother’s eye and pay no attention to the plank in your own eye?  How can you say to your brother, ‘Let me take the speck out of your eye,’ when all the time there is a plank in your own eye?  You hypocrite, first take the plank out of your own eye, and then you will see clearly to remove the speck from your brother’s eye.”  

In Psalm 139:19-22, the psalmist is judging others and extoling his own righteousness.  Even though his observations might be correct, while he’s rebuking God’s inaction to judge them, he became increasingly aware of the plank in his own eye.  He turned his focus to a humble request.  Listen to his plaintive cry: “Search me, O God, and know my heart; test me and know my anxious thoughts.  See if there is any offensive way in me.” 

He had anxious thoughts about the probability of offensive ways lurking in his own heart.  First, deal with this.  Then “lead me in the way everlasting.” 

In other words, let God handle His enemies.